The present invention relates to current switches and, more particularly, to a current switch for separating analog voice signals in a telephony system such as a combined speakerphone/handset integrated circuit providing switched speech communication.
Full phone systems combining speakerphone and handsets are well known. Typically, in these systems the default mode of operation is the handset receiver path. Hence, whenever the handset is lifted off-hook the speakerphone portion of the system is muted. However, in response to selecting the hands free speakerphone mode of operation the handset portion of the system must be automatically muted.
In order to successfully integrate the functions of a voice-switched speakerphone and a telephone handset network onto a single chip, it is necessary to be able to switch voice and dialing signals to the proper circuitry. Thus, depending on the mode of operation, the voice signal is heard at the speakerphone speaker or handset receiver only. Hence, a need exist for providing electronic switching of the voice signals between the speakerphone and handset circuitry depending on the proper mode of operation. Moreover, it is desirable to switch only alternating currents while maintaining direct current voltages in the signal paths constant to keep audible transients from being generated when the circuit is switched between modes.